The goal of this project is to test the hypothesis that the emergence of atypical voice quality in children with autism is an attribute of core impairments in social interaction against the hypothesis that voice quality disorders are an early outcome of comorbid motor deficits in vocal production in autism spectrum disorders (ASD). By cross-analyzing electroglottographic (EGG) recordings and longitudinal audio recordings of the home language environment for 80 children with and without ASD, we will be able to determine if acoustic measures of early vocal development can predict atypical voice quality outcome assessed with electroglottography. This will aid the development of efficient methods for early detection and treatment of voice quality disorders in ASD. The first specific aim is to characterize voice quality development in children with ASD, non-autistic developmental delays and typical development, using glottal source parameters estimated from EGG recordings at the age of 24 months. A novel video-based clinical assessment paradigm that we have specially designed to elicit vocalizations from children with autism will be used to collect EGG recordings from children. The second specific aim is to determine the relation between vocal development in the first two years of life and voice quality outcome at the end of the second year of life, by comparing developmental trajectories for acoustic measures of vocal production derived from home audio recordings to voice quality measures determined from EGG recordings. The third specific aim is to determine the correlation between voice quality measures, acoustic measures of vocal production and clinical assessment measures for deficits in speech motor control and social interaction in children with ASD. Accomplishing these three aims will reveal how voice quality disorders are associated with comorbid speech motor deficits and core impairments in social interaction in autism. This research addresses two themes in the IACC Strategic Plan: `Novel Research Strategies', and `Heterogeneity'.